code: def on_draw(self, ev):
      gloo.set_viewport(0, 0, *self.physical_size)
      gloo.clear(color="black", depth=True)
  
      for mesh in self.meshes:
          mesh.draw()
  
file_path: vispy/examples/basics/visuals/mesh.py
imports: import numpy
  from vispy import app, gloo, visuals
  from vispy.geometry import create_sphere
  from vispy.visuals.transforms import STTransform, MatrixTransform, ChainTransform
  from vispy.visuals.filters import ShadingFilter
label_desc: Use image node_id 4 for calling the Canvas obj's underlying member method code with example usage: obj.on_draw(ev) without return types